Steam producing process



y 1940- Q w.'D. LA MONT 2,201,624

STEAM PRODUCING PROCESS Original .Filed Oct. 5, 1953 5 Sheets-Sheet 1 INVENTO 1 W6! Zfer Dougl 14 BY ATTORNEY y 1940- w. D. LA MONT 2,201,624

STEAM rnonucme PROCESS Original Filed Oct. 5, 1933 '3 Sheets-Sheet 2 if? 100/! 217 51 1 7 Z07 36 5,12

I I l I l l I INVENTOR. Wa/fer flouglqs lei/40m y 21, 1940- w. D. LA MONT 2,201,624

STEAM PRODUCING PROCESS Original Filed Oct. 5, 1933 5 Shets-Sheet 5 10/ Z INVENTOR Wall/0r Douglas [cl/V012! Patented May 21, 1940 I UNITED STATES PATENT OFFICE 2,201,62 STEAM PRODUCING rnocnss Original application October 5, 1933, Serial No.

692,236. Divided and this application December 25, 1934, Serial No. 759,131

13 Claims.

This invention relates to high speed steam and power producing apparatus and high speed methods of operating the same.

This application is a division of my application Serial No. 692,236, filed October 5, 1933.

The method of steam generation in accordance with the present invention makes possible semiunidirectional flow of the main working fluid in my steam generating elements under conditions of high temperature radiant and convection heat transfer at high rates of heat release.

A main object of my invention is to reduce the size, weight, and cost of high speed steam producing apparatus. I do this by increasing its speed of operation, the detailed means and methods of which are in this case.

By my improved methods of operating steam boilers, I insure their continued performance under long sustained overload conditions through many years of life up to the limit of the maximum heat load conditions for which they are designed, without destroying the boiler, practically regardless of how rapidly combustion temperatures, or load conditions may change, or

- how fast fluids in all my boiler high speed fluid streams may flow with my improved methods of supercharging and coordinating their various velocities.

It is vital that the main working fluid especially, flow at least semi-unidirectionally at all times, under 'all steam making loads and speeds, substantially regardless of firebox temperatures or rates of heat release.

In my previous inventions, as disclosed in reissued U. S. Patent 16,895 and U. S. Patent 1,884,979 and others, using less than suflicient water than would normally be required to fill boiler tubes, I endeavored. to secure uni-directional flow of my main working fluid flowing through radiant heat recelving'water'wall tubes, each tube of considerable length, and of small size, and preferably substantially uniform diameter to insure rapid radiant and convection heat pick up.

Several difliculties'were present. When firebox, or so-called combustion'chamber pressures, on unburned gases and on burned gases remained down around a few inches of water, and- I employed forced circulation with orifices or restrictions, for pressure drop delivery and water dis tribution purposes at or near the inlet for working fluid entering each long, small diameter boiler tube in my boilers preferably having constant circulation of water through a steam and water separating device I found in the case of fluid fuel fires, a tendency for these fires to rove back and forth or here and there in the combustion chamber, momentarily intensifying locally certain heat receiving areas in the tubular water wall while these tubes carried rapidly fiow- 5 ing water in their interiors.

With stoker fires it was possible, in each individual installation of water wall in the firebox, when said water wall comprised long tubes of small diameter in accordance with my previous water wall inventions, not using so-called full tubes, to experimentally determine where local hotter areas were, and to provide larger orifices in the water wall tubes passing through these areas and/or accomplish larger pressure drops through the orifices. ,This preliminary experimental work of determining exactly where local hotter areas were and provide larger orifices in the water wall tubes passing through these areas and/ or larger pressure drops through the orifices, was no matter for a novice to undertake, because often in boilers of identical design, intensely hot areas would be found in diiferent places in the walls of the combustion chamber, and further, would wander as fire box temperatures changed, not similarly, for some unaccountable reason, even though all factors may have appeared identical. I

With hotter, higher speed, fluid fuel fires, this wandering action becomes a roving action, of great intensity and suddenness, abruptly delivering, or failing to deliver, heats rapidly to certain sections of waterwall tubes at various localized areas, always impossible to determine in advanceand' constantly changing in position.

These abrupt changes in'the heat supplied at localized and constantly varying water well heat reception areas are due to combustion conditions in the firebox changing constantly.

When rates of heat release or the temperatures in the combustion chamber raised to a high point, steam or water delivery from the outlets of the tubular water wall members develop a rhythm, the wall pants, (with a noise somewhat like a fatigued animal), the tubesrhythmically belch- 45 ing steam and water, pausing or gulping in their steam and water delivery, then belching more I steam and water. The water wall tubes as a whole when acting in the above manner using my pump circulation with orifices at the inlet of the tubes and less than enough water to fill the tubes throughout the length of the tubes, positively deliver water and steam in one path flow to the tube inlets, but this working fluid de livery at the outlets, and throughout the length of the tube intermittent. It is not continuously uniform nor is it semi-unidirectional nor unidirectional.

There is a distinct difierence in the operating characteristics of a so-callcd full water tube making steam, compared to a tube in which steam is being produced with less than sufficient water to fill the tube; especially when tubes of both types are subjected to exceptionally high rates of heat release, and the condition of semiunidirectional or unidirectional fiow of working fluids is considered.

Other objects of my present invention are to attain a positive and controlled supply of water to each of the steam generating tubes or elements conveying working fiuid through the water wall surrounding the combustion zone and through the steam making elements exposed to convection heat; to provide steady and continuous circulation of the water through the water passages or tubes of the water wall or water wall boiler and steam generating elements exposed to convection heat; to provide for the proper and adequate fiow of water through the different parts of the steam generating apparatus and in such relation to the steam generated in said parts or to the condition of the steam generated therein that an adequate flow of water may be maintained through each part and in suitable relation in one part relative to the other. It is a still further object of the invention to provide for the positive control of the amount of water delivered to or fiowing through the different parts and to control the conditions under which it flows so as to accomplish the proper delivery to and flow through the different parts of the steam generating apparatus to suit conditions of steam generation in said parts.

A still further object of the present invention, is to increase the amount of water circulated and therefore the speed of the circulation of steam and water in the tube with the increase in the rate of heat release, in order to increase the rate of heat transfer from the metal of the tubes to the water and the steam by moving the forming bubbles of steam away from their point of formation faster, thus protecting the Water wall tubes especially, and the other tubes of the boiler from the increasing heat to which they are exposed with every increase in the rate of heat release in the combustion chamber.

An important object of this invention is to disclose how so-called full waterwall tubes can be operated with positive input of water into each tube in sufficient quantity to protect each tube regardless of how rapid rates of heat release are obtained in the combustion chamber, up to the maximum heat effects for which it is designed to withstand; and to show and describe how semi-unidirectional fiow of steam and water within and throughout a portion of the length of the tube can also always be uniformly obtained under any combustion chamber heat releasing condition for which it is designed.

In accordance with my invention, the placing of pressure drop devices beyond the water inlet end of the tubes, or in that part of the tube exposed to radiant and/or convection heat, is a preferred position for these pressure drop devices, or orifices, if orifices are used as pressure drop devices.

Also in accordance with my invention, the pressure drop devices are placed preferably at any point in the tube beyond the point where 2,201.,eaa

steam begins to form, at the designed rate of heat release for the steam generator, thus insuring under the proper load conditions, the passing through the pressure drop device of at least some steam with the water.

This immediately gives the advantage of a larger area for steam and water passage through the pressure drop device for a given pressure drop, and a given quantity of water, than would be possible if water alone were passed through the pressure drop device. v

This new position of my pressure drop device is also of immediate advantage to reduce the possibility of clogging, whether the steam generator is used, as in my present invention, operating a part of the steam generating tube with a so-called full tube condition, or if the heat release permits, and it is desirable to operate a part of the steam generator under conditions of my previous inventions using less than enough water than is normally required to fill the tube.

However, the most desirable position of my pressure drop device is at that position of the length of the tube which at the maximum rates of heat release for which it is designed will insure a suflicient length of the tube to give unidirectional fiow of the working fluid so that the steam generator operating as a whole will not have serious steam and water surging conditions caused by that part of the tube in which unidirectional flow is not insured. A steam generating apparatus operating in this way has certain advantages over certain of my previous boiler inventions (using steam generating tubes with less than enough water to fill the tubes in their steam generating portion). Where the rate of heat release is not too great, my new type of steam generator, as outlined herein, can be profitably used.

With the orifices at the inlet end of the tube, as outlined in my reissued U. S. Patent #l6,895 and my issued U. S. Patent #1384379, and in other patents of mine, practically the whole length of the tube is subject to a surging action as the rate of heat release increases, especially if the tube is operated with the less than enough water to fill condition. Such a steam making tube has a non-compact, elastic column of steam and water throughout its length. Sudden high heat efiects on a local section of the tube will cause sudden local increase in pressure acting both ways and causing a compression of the column toward the inlet end, as well as toward the outlet end, resulting in a back and forth flow of steam and water in the tube past the orifice which may become violent enough to interfere with the proper operation of the boiler.

By advancing the orifice toward the outlet end of the tube, as in the present invention, the proportion of the length of the tube behind the orifice which has a compact column of steam and water, increases; and the proportion of length past the orifice toward the outlet end, which is subject to the surging action, decreases; reducing the degree of interference to proper steam making operation from back and forth flow or surging flow. The tube under this condition has an assured unidirectional flow for that part of its length between the orifice and the inlet end, while the part of the length from the orifice to the outlet end may have some degree of surging or non-unidirectional flow. This results in the tube as a whole giving what is termed semiunidirectional flow. v

As the rate of heat release increases, the need all of advancing the orifice along the tube, toward the outlet end of the tube, likewise increases, until the exit end of the tube is finally reached. This is further discussed in my copending application Serial No. 686,268, filed August 22, 1933.

The selection of the point along the length of the tube where the orifice can best be used is a matter of the general duty for which the apparatus is designed and for which it is to be put in use. The main factors to be considered are,

1. The rate of heat release in the combustion zone.

2. The degree of fluid compactness required to prevent surging in the hydraulic colunm from behind the orifice to the inlet end of the steam generating tube.

3. The degree of fluid compactness required to prevent surging in the hydraulic column from immediately beyond the orificeto the outlet end of .the steam generating tube, in which some surging can be permitted without interfering with the proper steam making operation of the boiler.

4. The amount of water most desirable for circulation.

5. The degree of pressure drop required to insure one path flow and/or semi-unidirectional fiowof the working fluid.

' 6. The size of orifice, or pressure drop device desirable to avoid clogging.

7. Mechanical and boiler cleaning considerations. a

8. The question as to whether it-is better to operate a portion of the steam generating section win the so-called full tube condition, or with less than suflicient to fill the tubes condition.

In practical application of my previous inventions, using an orifice at or near the entrance to the tube and passing only water through it, I'

found, especially in waste heat work and with water wall tubes of very short length exposed to moderate rates of heat release; that a very small diameter holefor the orifice in each tube was required to pass the proper amount of water into the tube for the protection of the tube without circulating an unnecessarily large amount of water and to still have a pressure drop of sufficient amount to insure one path flow into the tube.

Without use of distilled water,

bonates is used; this small oriflceat the entrance to each tube, presents a serious problem to prevent clogging which screening of the circulation water line, and of orifices, does not entirely eliminate.

As previously stated, I found that if the orifice is placed at a point in the steam generating element where both steam and water is passed,- a much larger hole. can be used, or with other forms of resistgrs or pressure drop devices, much larger areas can be used. This is due to the great increase in the volume of steam compared to water per 1b., of either.

If the orifice is placed beyond the point in the tube where steam begins to form there is also a marked increase in the size of the hole which can be used to pass a given amount of water with a of steam with the excess water.

or in cases where water containing large amounts of car- I have found that with steam generator units, designed for certain load conditions, using an economizer that gives considerable -.steam generation at full load, or with an economizer which steams; the art of placing the orifice or pressure drop device at the proper position along the length of the economizer tube to insure semiunidirectional fiow may be used in the same way as previously outlined for waterwall and convection generating tubes. The placing of the orifice or pressure drop device past the point where steam may form is especially advantageous in the economizer to permit the use of larger orifices or pressure drop devices than would be possible if feed water only passed through such devices with sufficient pressure drop to insure one path flow under full load conditions.

A prime object of the present invention is to increase the speed of steam generation and power production, thus making my steam generating apparatus and my steam power plant smaller, lighter weight, and less expensive.

In one of its aspects my invention is a high speed steam generator whose water walls in the radiant heat releasing and receiving area, namely the combustion zone, and whole steam generating tubes exposed to convection heat transfer in the convection heat zone, will not give an undue amount of surging of steam and water travelling back and forth in the tubes but will have positive semi-unidirectional flow of water in each wall tube, at all times, regardless of combustion conditions in thefirebox or the size or movement of large steambubbles shifting from side to side in individual water wall tubes; or group of water wall tubes, up to the maximum rate of combustion at which the steam boiler is designed to operate.

This present invention is particularly concerned with the improvement of high speed steam boilers, .and methods of operating said boilers. Where my invention, and/or any of its features, applies to flash boilers, such improvements are well within the scope of my invention as herein described.

While my invention has been described herein as relating to steam generating apparatus which is intended especially for the generation of steam from water, it will be understood that the terms ."steam and water as used in the specifications and claims are intended to include as equivalents any liquids which might be handled by the novel process and/or apparatus herein described, resulting in the generation of any vapors which might be handled by or be useful in connection with my process and/or apparatus, and it will also be understood .that many of the novel features .of this invention are applicable in other fields than that for which the apparatus herein specifically illustrated and described is particularlyqintended.

Other objects and features will be particularly pointed out and disclosed hereinafter in the illustrations, descriptions, specifications and claims of this present patent application.

In the drawings:

Fig. 1 is a complete view of a power plant opcrating ina'ccordance with certain modifications of my invention.

Fig. 2 is a section taken along the lines 'A-A of my high speed steam boiler shown in Fig. 1;

Fig. 3 is one method of placing an orifice or pressure drop device in my working fluid heating element;

Fig. 4 is a view partially in elcvationand partially in section of one of my preferred forms of one of my working fluid steam generating waterwall elements attached to its intake manifoldand its outlet manifold as shown in Fig. 1 in accordance with my present invention;

Fig. 5 is a diagrammatic view of a down flow tubular water wall in a radiant heat releasing firebox or combustion zone made in accordance with my invention and wherein the fuel air mixture and the burned gases travel practically parallel to the water flowing in the water wall tubes;

Fig. 6 is similar to Fig. 5 the difference between the two figures being that here the fuel gases, unburned and burned, travel in countercurrent relation to the high velocity flow of the main working fluid in the water wall tubes;

Fig. 7 illustrates a coil type of water wall diagrammatically the coils leading the water upward, the flow of unburned and burned gases also being upward; the circulating pump preferably has a separate wheel for each steam generating tube to discharge water directly and only to the tube connected to it;

Fig. 8 is a similar diagrammatic view of that in Fig. 7 wherein the coils forming a water wall or a liquid wall of working fluid around the firebox or combustion chamber lead the water upward while the unburned and burned gases flow countercurrent or downwardly; the circulating pump preferably here again having a separate Wheel (or plunger, if a reciprocating pump is used) for each tube, to discharge directly into and maintain hydraulic pressure inside of each water tube;

Fig. 9 is a complete power plant showing the direction, the various fluids flow in their respective paths through my boiler and the close inter-relation between the action of the boiler and my high speed power plant as a whole of which my boiler forms a part;

Fig. 10 is a plan view of one of my fluid heat absorbing elements, with its pressure drop device as shown;

Fig. 11 is an enlarged detailed assembly drawing partially cut away, partially in elevation and section of parts of my high speed steam boiler;

Fig. 12 is a view looking downward on the top of the boiler (reduced in size) showing the turbine driven air supercharger delivering air tangentially to my boiler and a pipe releasing burnt gases tangentially;

Fig. 13 is a detail of Fig. 1, showing the path of travel of burnt gases as applied in connection with my new methods of heat extraction and heat transfer to the working fluid of the boiler;

Fig. 14 is an enlarged view of certain of the working fluid tubes or steam generating elements shown in other figures of the drawings;

Fig. 15 is an enlarged sectional view of my heat interchanging tube with longitudinal fins attached;

Fig. 16 is a sectional view of several heat interchanging tubes as they are arranged in the assembly sectional view shown in Fig. 13.

In Figure 1 of the drawings is shown a power plant including, as a part thereof, a steam generator adapted to produce steam of high energy content, in accordance with the present invention. The steam generator is designated by I, having a plurality of steam generator water wall tubes 34 therein receiving water from the water wall inlet header 33, and discharging water and/or steam to the steam generator outlet water wall collecting header 36. These tubes are exposed to a source of radiant heat produced by a flame fed with fuel from burner 2 in the burner throat 3. The combustion of the fuel oil is assisted by a source of air which may be supplied from the supercharger 5, to which air is admitted through inlet 4!, feeding air through the discharge lead 4 to the burner throat. The steam generator tubes are shown fitted with pressure drop devices 35, for controlling the input of water into each tube in sutficient quantity to protect the tube and to control the flow of steam and water in each tube to insure the proper operation thereof, said pressure drop devices being placed in an intermediate portion of the length of each tube, in accordance with the present invention. These devices are shown in greater detail in Figures 3 and 4.

The steam and water collected in header 36 discharges by way of conduits 31 (Figure 2) into water level cylinder 8 for maintaining a water level in the system, furnishing reserve power, and insuring water supply to the circulating pumps. The steam is separated from the water in the cylinder 8, and passes through the main high pressure steam line 9, having main control valve 31 therein for controlling the steam to the main turbine l0. Furthermore, a pipe line 1 extends from the upper end of cylinder ll to auxiliary steam turbine 5 having control valve 42 therein for controlling the drive of auxiliary turbine 6, which drives the air supercharger fan 5, fuel oil pump 21, boiler feed pump I! and boiler circulating pump 25.

The main exhaust lead In from the main turbine extends from the latter to the main condenser ll. Pipe I 2 represents the inlet for circulating cooling water to the main condenser ii, and pipe I 3 is the outlet pipe therefor. Pipe M is the condensate water discharge from the main condenser II to the main feed tank 15 therefor. Vent 4"! is associated with the feed water tank, and suction lead 29 extends from the latter to the condensate pump IE or feed pump ll. i8 is a discharge pipe connecting feed pump I! with the water level cylinder 8; IQ is a by-pass line for by-passing feed water around the feed pump l'l through water level regulator valve IQ, for controlling the water level in the system; and 20 is a feed stop and check valve on the feed pump discharge lead ill for stopping 5nd checking the feed of water into the sys- Associated with the cylinder 8 is a safety valve 2! for the boiler at the top of the cylinder, and a blow-01f valve 22 at the bottom thereof. The cylinder has a gauge glass 23, and an automatic water level regulator 24 from which extends a pipe 25 to the control valve 49.

lhe main steam generator circulating pump is represented at 26. The suction line for pump 26 is connected with the water level cylinder B, through pipe 3|, and the discharge pipe 32 of this pump extends therefrom to the inlet header 33. The main circulating pump is fitted with a bypass 65 therearound, to control the quantity of water which is circulated by means of control valve 44 in this by-pass.

The fuel oil tank is represented at 33 with its suction line 39, vent 5B, filling line it, and control valve therefor, 59, and burner by-pass return oil discharge lead Gl Opening into the fuel line into the burner is a pipe having a control valve therein M for introducing starting oil into the burner, and BI is a valve for shutting off the oil normally used in the operation of the having feed water inlet 46 and control valve 13 plant, while using the starting fuel oil. Pipe 28, constituting the exhaust lead from the auxiliary turbine 6, opens into the main turbine exhaust lead I0 Figures 5 and 6 show schematically arrangements similar to that shown in Figure 1. In Figure 5, the fuel air mixture and burned gases travel substantially parallel to the flow of water in the steam generator tubes .fitted with pressure drop devices 35 at intermediate points of the length thereof, in accordance with the present invention. In Figure 6, the gases travel in a counter-current direction to the direction of the flow of water.

Figures '7 and 8 show spiral sets of water wall generator tubes fitted with pressure drop devices 35 with each set having an individual circulating pump 26 26 and 26.

In Figure 9 is shown a complete high speed power plant embodying the highly eflicient boiler generating superheated steam. The circulating system for water and fuel resembles that illustrated in Figure 1, and a detailed description of the duplicate parts will not be set forth below. i

The central combustion chamber I06, as shown, has water wall tubes 34 therein through which water is circulated from inlet header 33 to outlet header 36. The steam and water produced in accordance with the present invention, is discharged into the tube 31 at the end of the boiler.

opposite the burner, and thence-to the water level cylinder 8 where it strikes a baflie plate BP which causes the water in the mixture to be separated and to drop by gravity whereas the steam accumulates at the top of the cylinder for passage therefrom. Tube 5I extends from the upper end of the cylinder 8 at 5 I to deliver saturated steam therefrom to the superheater tubes coiled around the interior of the combustion chamber which are shielded by the water wall tubes 34.

In addition to the steam generating tubes 34 in the combustion chamber, auxiliary steam generating tubes 52 are coiled in annular passage I00, formed on the outside of the combustion chamber I06, and confined by an external wall 202, which forms a tapered passage extending from the inlet thereof at I01, to the outlet thereof, at I09. The combustion gases travel upwardly to the top end of the chamber I06 and then pass through passage I01 downwardly, through the passage I08, giving up the heat contained therein to the steam-generating tubes 52. The tubes 52 may be supplied with circulating water from the main steam generator circulating pump 26 and these tubes discharge the steam and water therein into the water level cylinder at 52 These tubes 52 in the convection passage may be provided with fins 52 and 52, extending in parallel to the axis of the tubes, as shown in Figures 14, 15 and 16, for the purpose of more efl'ectively extracting the heat from the combustion gases.

In addition to the steam generating tubes 34 and 52 described above, tubes 55 may be provided for protectingthe combustion chamber inlet wall 205, which receive water from the inlet header 33 and discharge water and/or steam to the collecting header 36.

The combustion gases passing downwardly through the convection passage I00, pass through the exits I00 into a series of spirally disposed burnt gas passages H0. These spiral passages terminate near the top of the boiler into a passage III, which open into a common outlet passage II2, to which is connected the tangential stack outlet passage I I 3 opening into the atmosphere.

changing relationship with the burntgas passages I I0. The air is supplied from the air supercharger 60 (Figure 12), to the pipe I00 opening tangentially into the casing of the-boiler 20I. This casing forms in conjunction with the walls 203 forming the passages I I0, a plurality of spiral air-preheater passages IOI, which travel downwardly in Figures 9 and 11 towards the air inlets I03.

In the boilers shown in Figures 9 and 11, an inspection and ignition port I05 is provided covered by detachable closure 2I2.

The constituent parts of the boiler in accordance with the present invention are preferably constructed of non-corrosive metal alloys. With such a construction it is necessary to properly and thoroughly protect the metal walls from exposure to excessive heat effects from the radiant gases. This is accomplished by placing cooling protective surfaces in front of and in contact with the metal walls.

I claim:

ing air and fuel, burning said mixture in a combustion zone, placing liquid working fluid in heat exchanging relation to said burning mixture in said combustion zone thereby producing a mixture of liquid and vaporous working fluid, maintaining a liquid and vapor separation zone, maintaining a liquid level'in said separation zone, subjecting said mixture continuously to a drop in pressure at a point inthe path of flow thereof, and admitting said working fluid mixture continuously to said separation zone above said liquid level.

2. The method of steam generation which comprises mixing air and fuel, burning said mixture in a combustion zone, continuously circulating a liquid working fluid in heat-exchanging relation to said burning mixture to produce a mixture of liquid and vaporous working fluids, subjecting said mixture continuously at an intermediate pointof flow thereof to a drop in. pressure, and

heat-exchanging relation to said burning mixture to produce a plurality of streams containing a mixture of liquid and vaporous working fluids,-

subjecting each stream of the mixture continuously at an intermediate point of flow thereof to a drop in pressure, and separating the liquid working fluid from the vaporous working fluid for recirculation in the liquid working fluid circuit.

4. The method of steam generation which comprises mixing air and fuel, burning said mixture in a combustion zone, maintaining a convection gas zone in heat exchanging relation to and outside of said combustion zone, continuously emptying burned gases from said combustion zone into said convection zone, placing liquid working fluid in heat exchanging relation to said burning mixture in said combustion zone, placing said liquid working fluid in heat exchanging relation to said burned mixture in said convection gas zone, and subjecting said liquid working fluid to a-drop in pressure at a point in the path of flow of said mixture in said combustion zone.

5. In a steam making process, the steps of .mixing air and fuel, burning said mixture in a combustion zone, placing liquid working fluid in heat exchanging relation, to said burning mixture in said combustion zone thereby producing a mixture of liquid and vaporous working fluid, maintaining a liquid and vapor separation zone, maintaining a liquid level in said separation zone, subjecting said mixture continuously'to a drop in pressure at a point in the path of flow thereof, and admitting said working fluid mixture continuously to said separation zone above said liquid level and outside of the range of heat of said burning mixture. I

6. In a vapor generating process the steps of constantly circulating working fluid under pressure, dividing said working fluid in its liquid state into a plurality of separate liquid working fluid streams, placing said separate fluid streams each under pressure, transferring heat to said separate fluid streams, reducing the pressure on the liquid-vapor mixture by a pressure drop at an intermediate point ineach of said separate fluid streams, reassembling said separate fluid streams, separating liquid working fluid from its vapor for recirculation in the liquid working fluid streams, and removing said vapor from said circuit.

'7. A process as set forth in claim 6 wherein heat is transferred to said separate fluid streams by the circulation of the heating medium countercurrent to the flow of working fluid in said streams.

8. A process as set forth in claim 6 wherein heat is transferred from a combustion zone to said separate fluid streams coiled about said combustion zone.

9. A process as set forth in claim 6 wherein heat is transferred from a combustion zone tc said separate fluid streams whirling about said zone countercurrent to burned gases moving through said zone.

10. A process as set forth in claim 6 wherein said separate fluid streams of liquid-vapor working fluid mixture are reassembled in a liquid and vapor separating zone in which a liquid level is maintained.

11. A process as set forth in claim 6 wherein heat is transferred to said separate fluid streams by the circulation of the heating medium countercurrent to the flow of working fluid in said streams and wherein said separate fluid streams of liquid-vapor mixture are reassembled in the liquid and vapor separating zone wherein a liquid level is maintained.

12. A process as set forth in claim 6 wherein heat is transferred from a combustion zone to said separate fluid streams coiled about said comvbustion zone and wherein said separate fluid streams of liquid-vapor mixture are reassembled in a liquid and vapor separating zone wherein a liquid level is maintained.

13. A process as set forth in claim 6 wherein heat is transferred from a combustion zone to said separate fluid streams whirling about said zone countercurrent to burnt gases moving through said zone and wherein said separate fluid streams of liquid-vapor mixture are reassembled in a liquid and vapor separating zone wherein a liquid level is maintained.

WALTER DOUGLAS LA MONT. 

